He was also captain of the national side that won Italy's first ever UEFA European Championship on home soil in 1968, where he was also elected to the team of the tournament.

Born in Treviglio, in the Province of Bergamo (Lombardy), Facchetti began his career with his hometown club, GSD Mario Zanconti, as a forward, due to his pace, powerful shot, and technique.

[8] While playing for Trevigliese, he was noticed by Helenio Herrera, then manager of Inter, who launched him in Serie A in the late 1960–61 season as an attacking full-back on the left, due to his physique, energy, and tackling ability, in addition to his offensive attributes; he made his club and top-flight debut on 21 May 1961, in a 2–0 away win over Roma.

Facchetti's innovative playing style as one of the first European overlapping full-backs, combining hard defending with offensive prowess, played a key role in the defensive, yet counter-attacking catenaccio system of Herrera's "Grande Inter" side that dominated Italian, European, and World Football in the 60s; whilst conceding few goals defensively, Facchetti was also able to contribute offensively with numerous goals and assists.

[11] Facchetti spent his entire professional career with Inter, later captaining the side, after Armando Picchi, Mario Corso and Sandro Mazzola, during his final season with the club, between 1977–78.

[3][9] Regarded as one of the greatest full-backs of all time, Facchetti's pace, stamina, power and excellent physical and technical traits allowed him to excel as an offensive full-back or wing-back; a former forward and midfielder, he was known for his ability to make attacking runs down the left flank and get into good offensive positions in the area which allowed him to either score or assist goals, due to his powerful shot and crossing ability, and was known for his tendency to cut into the centre in order to strike on goal, which was very unusual for full-backs at the time.

[5] Over the years Facchetti held various managerial positions at Inter Milan, including technical director,[9][18] board member,[19] worldwide ambassador,[citation needed] and vice-chairman.

Palazzi presented a report on the Calciopoli bis investigation, originating from facts that emerged in the related criminal proceeding in Naples and at the time judged not relevant in the sporting trial five years earlier, in which, among others, Facchetti was accused of violating Article 6 of the then Sports Justice Code,[21][22] which was an offense consisting of "a consolidated network of relationships, of a non-regulatory nature, directed to alter the principles of impartiality, impartiality and independence of the refereeing sector", actions that Palazzi judged to be "certainly aimed at ensuring an advantage in the standings for Inter".

The judge dismissed the lawsuit and acquitted Moggi, finding "with certainty a good truthfulness" in his statements and citing the existence of "a sort of lobbying intervention on the part of the then president of Inter towards the referee class ... , significant of a relationship of a friendly [and] preferential type, [with] heights that are not properly commendable.

Known for his discipline as well as his playing ability throughout his career, the Premio internazionale Giacinto Facchetti was also established in his honour later that year, and is currently awarded annually to a football personality who was stood out for their honesty, correct behaviour, and sportsmanship.

[9][34] Facchetti is featured in the football video game FIFA 14's Classic XI – a multi-national all-star team, along with compatriots Bruno Conti, Gianni Rivera, and Franco Baresi.